The Wall Street Journal is reporting that Apple has now acquired another company, the social-media analytics startup Topsy Labs Inc. for more than $200 million, according to people familiar with the matter.

Billed as the world’s only index of the public social web, Topsy builds software that ties into Twitter to enable social search and crazy detailed analytics.

Apple has confirmed the deal, but its spokesperson refused to detail what the company’s plans with Topsy might be. Since we doubt Apple is building its own search engine, Topsy intelligence could be plugged into Siri as yet another data provider for greater social context and improved search.

As you know, Apple with iOS 7 added the ability to check out a contact’s Twitter feed via Siri. Another possibilities: Apple’s iTunes Radio service and the struggling iAd platform…

Topsy specializes in data from Twitter, TWTR -1.90% offering tools to analyze tweets and other information to help track consumer sentiment. Its tools can decipher how often a specific term is tweeted, find an influential person on a specific subject, or measure the exposure of an event or campaign.

The company is one of a handful of Twitter’s partners who have access to the so-called “firehose”—the full stream of all tweets posted to the service. Topsy competes with DataSift Inc. and Gnip Inc. to analyze and resell this data to customers.

An Apple spokeswoman has confirmed the deal with the company’s standard boilerplate on buying smaller technology companies from time to time. “We generally do not discuss our purpose or plans,” she said without elaborating further.

In addition to potential Siri uses, Apple could tap Topsy to boost iTunes Radio by providing the ability “to alert listeners to songs that are trending or artists being discussed on Twitter,” the article speculates.

@jyarow@dherman76 my guess, their indexing tech which they’ll use to index apps to improve Siri/search. Twitter integration is irrelevant

And if Siri and/or iTunes Radio are in the cards, what’s stopping Apple from using Topsy technology to improve the accuracy of its iAd advertising platform, which happens to power ads in the free version of iTunes Radio?

As the article notes, “Topsy also could provide marketers with real-time data to sell targeted advertising on iTunes Radio”.

And while we’re speculating, Topsy could be a nice fit to boost Apple’s many content stores by delivering content recommendations on the iTunes Store, App Store, Mac App Store and the iBooks Store based on Twitter trends.

It’s interesting that Topsy’s Pro Analytics service is in use at some of the world’s leading global marketing, news, publishing, TV/movie/entertainment and financial organizations.

For what it’s worth, Topsy’s products include the Social Search engine which taps into Twitter to figure out what you did on the popular micro-blogging platform last summer, as well as detailed Analytics and API services.

From Topsy’s website:

With the only full-scale index of the public social web, instantly analyze any topic, term or hashtag across years of conversations on millions of web sites.

Identify key thoughts, opinions and content, over time or in realtime. Dynamically reveal related ideas and unexpected insights.

Use precise metrics to model current trends against competitors or past events. Design and optimize actions, or predict future outcomes.

The Topsy API is especially interesting – it allows developers to easily implement social features into their software using social content, metrics and insights from Topsy.

The company’s website positions Topsy as “the only Twitter partner certified as both a data reseller and an analytics provider”. Greg Sterling of SearchEngineLand has a nice profile on Topsy: the firm sits on an astounding 540 billion tweets in its index.